1. Field of the Invention
The present invention relates to an adhesive composition which is in a wax-like or jelly-like state at room temperature.
2. Description of the Prior Art
An adhesive of the type that is inserted in a container in the solid state, pushed out of the container for use, spread over adherend surfaces, and then the remainder re-inserted in the container for subsequent use is generally known as a solid adhesive.
In such a solid adhesive, it is required to blend a gelling agent in a binary composition system comprising an adhesive component and a solvent, and as such gelling agents there are alkali metal salts or ammonium salts of fatty acids as described in U.S. Pat. No. 3,576,776 and benzalsorbitols as described in Japanese Patent Application (OPI) 29,434/72. However, the use of the fatty acid salts or fatty acid soaps described in the aforesaid U.S. Patent as a gelling agent is accompanied by problems, e.g., the adhesive composition produced usually shows high alkalinity (about 10 pH), which creates a safety problem when it is handled by school children, etc., as well as it takes a long time to produce the adhesive composition and the viscosity of the adhesive composition is high (e.g., higher than 150,000 cps), which makes it difficult to fill the adhesive composition in containers.
When the benzalsorbitols disclosed in the aforesaid Japanese Patent Application are used as the gelling agent, it is necessary to use a comparatively large amount of a low boiling point organic solvent such as an alcohol as the solvent for the production of the adhesive since the benzalsorbitols are insoluble or sparingly soluble in water, and, hence, the adhesive composition obtained has the essential fault that the solvent volatilizes during storage or use of the adhesive composition even at room temperature, as well as the fact that the vapor of the solvent volatilized is harmful to humans.